// addrspace.cc 
//	Routines to manage address spaces (executing user programs).
//
//	In order to run a user program, you must:
//
//	1. link with the -N -T 0 option 
//	2. run coff2noff to convert the object file to Nachos format
//		(Nachos object code format is essentially just a simpler
//		version of the UNIX executable object code format)
//	3. load the NOFF file into the Nachos file system
//		(if you haven't implemented the file system yet, you
//		don't need to do this last step)
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "system.h"
#include "addrspace.h"
#include "noff.h"
#include "table.h"
#include "synch.h"

extern "C" { int bzero(char *, int); };

Table::Table(int s) : map(s), table(0), lock(0), size(s) {
    table = new void *[size];
    lock = new Lock("TableLock");
}

Table::~Table() {
    if (table) {
	delete table;
	table = 0;
    }
    if (lock) {
	delete lock;
	lock = 0;
    }
}

void *Table::Get(int i) {
    // Return the element associated with the given if, or 0 if
    // there is none.

    return (i >=0 && i < size && map.Test(i)) ? table[i] : 0;
}

int Table::Put(void *f) {
    // Put the element in the table and return the slot it used.  Use a
    // lock so 2 files don't get the same space.
    int i;	// to find the next slot

    lock->Acquire();
    i = map.Find();
    lock->Release();
    if ( i != -1)
	table[i] = f;
    return i;
}

void *Table::Remove(int i) {
    // Remove the element associated with identifier i from the table,
    // and return it.

    void *f =0;

    if ( i >= 0 && i < size ) {
	lock->Acquire();
	if ( map.Test(i) ) {
	    map.Clear(i);
	    f = table[i];
	    table[i] = 0;
	}
	lock->Release();
    }
    return f;
}

//----------------------------------------------------------------------
// SwapHeader
// 	Do little endian to big endian conversion on the bytes in the 
//	object file header, in case the file was generated on a little
//	endian machine, and we're now running on a big endian machine.
//----------------------------------------------------------------------

static void 
SwapHeader (NoffHeader *noffH)
{
	noffH->noffMagic = WordToHost(noffH->noffMagic);
	noffH->code.size = WordToHost(noffH->code.size);
	noffH->code.virtualAddr = WordToHost(noffH->code.virtualAddr);
	noffH->code.inFileAddr = WordToHost(noffH->code.inFileAddr);
	noffH->initData.size = WordToHost(noffH->initData.size);
	noffH->initData.virtualAddr = WordToHost(noffH->initData.virtualAddr);
	noffH->initData.inFileAddr = WordToHost(noffH->initData.inFileAddr);
	noffH->uninitData.size = WordToHost(noffH->uninitData.size);
	noffH->uninitData.virtualAddr = WordToHost(noffH->uninitData.virtualAddr);
	noffH->uninitData.inFileAddr = WordToHost(noffH->uninitData.inFileAddr);
}

//----------------------------------------------------------------------
// AddrSpace::AddrSpace
// 	Create an address space to run a user program.
//	Load the program from a file "executable", and set everything
//	up so that we can start executing user instructions.
//
//	Assumes that the object code file is in NOFF format.
//
//	"executable" is the file containing the object code to load into memory
//
//      It's possible to fail to fully construct the address space for
//      several reasons, including being unable to allocate memory,
//      and being unable to read key parts of the executable.
//      Incompletely consretucted address spaces have the member
//      constructed set to false.
//----------------------------------------------------------------------

AddrSpace::AddrSpace(OpenFile *executable) : fileTable(MaxOpenFiles) {
    NoffHeader noffH;
    unsigned int i, size, index, g;
    unsigned int codeSize, initDataSize;
    // Don't allocate the input or output to disk files
    fileTable.Put(0);
    fileTable.Put(0);
    DEBUG('a', "Reading in the executable\n");

    asExecutable = executable;

    executable->ReadAt((char *)&noffH, sizeof(noffH), 0);
    DEBUG('a', "After reading in the executable\n");
    if ((noffH.noffMagic != NOFFMAGIC) && (WordToHost(noffH.noffMagic) == NOFFMAGIC))
      SwapHeader(&noffH);
    ASSERT(noffH.noffMagic == NOFFMAGIC);

    DEBUG('a',"After reading in file\n");
    size = noffH.code.size + noffH.initData.size + noffH.uninitData.size ;
    numPages = divRoundUp(size, PageSize) + divRoundUp(UserStackSize,PageSize);
                                                // we need to increase the size
						// to leave room for the stack
    size = numPages * PageSize;

    numCodePages = divRoundUp(noffH.code.size, PageSize);
    numInitPages = divRoundUp(noffH.initData.size, PageSize);

    // Virtual memory is implemented so numPages can be greater
    ASSERT(numPages <= NumPhysPages);		
    // check we're not trying
						// to run anything too big --
						// at least until we have
						// virtual memory

    
    DEBUG('a', "Initializing address space, num pages %d, size %d\n", 
					numPages, size);

    // first, set up the translation 

    pageTable = new TranslationEntry[numPages];
    //bzero(machine->mainMemory, size);
    for (i = 0; i < numPages; i++) {
      index = bitmap->Find();
      if(index == -1) {
	// If index is -1, then the bitmap is full
	// and there are no available pages in physical page table
	DEBUG('a',"Bitmap is full");
	break;
      }
      pageTable[i].virtualPage  = i; // virtual page always starts at i 
      
      pageTable[i].physicalPage = index; // index will give us the position in main memory
      
      //pageTable[i].location     = 2;
      //pageTable[i].swapLoc      = NULL;
      pageTable[i].valid        = TRUE;
      pageTable[i].use          = FALSE;
      pageTable[i].dirty        = FALSE;
      pageTable[i].readOnly     = FALSE;  // if the code segment was entirely on 
                                          // a separate page, we could set its
                                          // pages to be read-only 
      
    
      executable->ReadAt(&(machine->mainMemory[index*PageSize]),PageSize,
			 (i*PageSize)+noffH.code.inFileAddr);
    }

    // zero out the entire address space, to zero the uninitialized data segment 
    // and the stack segment
    DEBUG('c',"OUT\n");
    // bzero(machine->mainMemory, size);

    // then, copy in the code and data segments into memory
    /*
    bzero(machine->mainMemory,size);
    if (noffH.code.size > 0) {
        DEBUG('a', "Initializing code segment, at 0x%x, size %d\n", 
			noffH.code.virtualAddr, noffH.code.size);
	
        executable->ReadAt(&(machine->mainMemory[noffH.code.virtualAddr]),
			noffH.code.size, noffH.code.inFileAddr);
	

	
    }
    if (noffH.initData.size > 0) {
        DEBUG('a', "Initializing data segment, at 0x%x, size %d\n", 
			noffH.initData.virtualAddr, noffH.initData.size);
	
        executable->ReadAt(&(machine->mainMemory[noffH.initData.virtualAddr]),
		noffH.initData.size, noffH.initData.inFileAddr);

	
    }
    */

}

void AddrSpace::memoryLoad(int vpnumber, int index) {
  NoffHeader noffH;
	    	      
  asExecutable->ReadAt((char *)&noffH, sizeof(noffH), 0);
  // Read this into memory
  asExecutable->ReadAt(&(machine->mainMemory[index*PageSize]),PageSize,
					     (vpnumber*PageSize)+noffH.code.inFileAddr);

}

//----------------------------------------------------------------------
// AddrSpace::~AddrSpace
//
// 	Dealloate an address space.  release pages, page tables, files
// 	and file tables
//----------------------------------------------------------------------

AddrSpace::~AddrSpace()
{
    delete pageTable;
}

//----------------------------------------------------------------------
// AddrSpace::InitRegisters
// 	Set the initial values for the user-level register set.
//
// 	We write these directly into the "machine" registers, so
//	that we can immediately jump to user code.  Note that these
//	will be saved/restored into the currentThread->userRegisters
//	when this thread is context switched out.
//----------------------------------------------------------------------

void
AddrSpace::InitRegisters()
{
    unsigned int i;
    DEBUG('r',"Init registers\n");
    for (i = 0; i < NumTotalRegs; i++)
	machine->WriteRegister(i, 0);

    // Initial program counter -- must be location of "Start"
    machine->WriteRegister(PCReg, 0);	

    // Need to also tell MIPS where next instruction is, because
    // of branch delay possibility
    machine->WriteRegister(NextPCReg, 4);

   // Set the stack register to the end of the address space, where we
   // allocated the stack; but subtract off a bit, to make sure we don't
   // accidentally reference off the end!
    machine->WriteRegister(StackReg, numPages * PageSize - 16);



    DEBUG('a', "Initializing stack register to %x\n", numPages * PageSize - 16);
}

//----------------------------------------------------------------------
// AddrSpace::SaveState
// 	On a context switch, save any machine state, specific
//	to this address space, that needs saving.
//
//	For now, nothing!
//----------------------------------------------------------------------

void AddrSpace::SaveState() 
{
  

}

//----------------------------------------------------------------------
// AddrSpace::RestoreState
// 	On a context switch, restore the machine state so that
//	this address space can run.
//
//      For now, tell the machine where to find the page table.
//----------------------------------------------------------------------

void AddrSpace::RestoreState() 
{
  // DONT NEED THIS SINCE WE ARE USING TLB 
  // PROJECT 3
  PageTableLock->Acquire();
  machine->pageTable = pageTable;
  machine->pageTableSize = numPages;
  


  PageTableLock->Release();
}
unsigned int AddrSpace::NumPages() {
    return numPages;
}
void AddrSpace::NewPageTable() {
  
  IntStatus old = interrupt->SetLevel(IntOff);
    PageTableLock->Acquire();
    int i, index;
    TranslationEntry *newPageTable;
    newPageTable = new TranslationEntry[numPages+8];

    for (i = 0; i < numPages; i++) {
      newPageTable[i].virtualPage = pageTable[i].virtualPage; 
      newPageTable[i].physicalPage = pageTable[i].physicalPage;
      newPageTable[i].valid       = pageTable[i].valid;
      newPageTable[i].use         = pageTable[i].use;
      newPageTable[i].dirty       = pageTable[i].dirty;
      newPageTable[i].readOnly    = pageTable[i].readOnly;  // if the code segment was entirely on 
                                                            // a separate page, we could set its
                                                            // pages to be read-only   
    }
    // Allocate space for new stack in address
    for(i = numPages; i < (numPages+8); i++) {
      index = bitmap->Find();
      if(index == -1) {
	// If index is -1, then the bitmap is full
	// and there are no available pages in physical page table
	DEBUG('a',"Bitmap is full");
	break;
      }
      newPageTable[i].virtualPage  = i;
      newPageTable[i].physicalPage = index;
      newPageTable[i].valid        = TRUE; 
      newPageTable[i].use          = FALSE;
      newPageTable[i].dirty        = FALSE;
      newPageTable[i].readOnly     = FALSE;
    }
    // delete old page table
    delete[] pageTable;

    // p4 may not need this 
    pageTable = newPageTable;
    machine->pageTable = pageTable;

    // Increase the number of pages by the number of new pages allocated to stack
    numPages = numPages+8;
    machine->pageTableSize = numPages;

    PageTableLock->Release();
    interrupt->SetLevel(old);
}

void AddrSpace::DeAllocate(int stackLocation){
  PageTableLock->Acquire();
  /*
    Need to fix this
  for(int i=0; i < numPages; i++) {
    pageTable[stackLocation+i].physicalPage = NULL;
    pageTable[stackLocation+i].valid        = TRUE; 
    pageTable[stackLocation+i].use          = FALSE;
    pageTable[stackLocation+i].dirty        = FALSE;
    pageTable[stackLocation+i].readOnly     = FALSE;
  }
  */
  PageTableLock->Release();
}

ProcessTable::ProcessTable() {
  
}
ProcessTable::~ProcessTable() {

}
